Sudoku Battle

In this game there will be a sudoku grid and all the players mark the grid at the same time. One point is awarded for each correct mark and one point is deducted for each wrong mark. In a sudoku grid, there will be a 9 x 9 grid of squares, some of the squares will be numbered. Each 3 x 3 squares are further grouped into regions, so there are a total of 9 regions. The object of the sudoku game is to put numbers 1 to 9 in the empty squares such that the numbers in the same row or column or region do not duplicate.